1. Field of Invention
The present invention relates to the field of lifting and leveling devices. More particularly, the present invention relates to a device for providing immediate and adjustable vertical support. More particular yet, the present invention involves an adaptive device for lifting and leveling structures such as trailers, where the device is pivotably mountable on the structure's underside and utilized manually with minimal effort.
2. Description of Prior Art
In the field of vertically adjustable support mechanisms for lifting and leveling, there are a variety of devices commonly referred to as jacks. Jacks are utilized in many different situations with any number of vehicles such as automobiles, trucks, buses, and recreational vehicles. More related to the instant invention, jacks are also used to lift, support, and level trailers. Such trailers may be open-bed or enclosed, may be a simple container-like structure, or may serve a specific function--e.g., car-carriers, horse-trailers, boat-trailers, camper-trailers including those known as "fifth wheels"--or the like. Jacks used for such trailers vary in both design and manner by which they operate. Such jacks may be electrically powered via a linear motor like a solenoid or via a rotary motor with gearing to transfer rotary motion to linear motion. Also, they may be hydraulically powered via a hydraulic cylinder unit. The hydraulic cylinder units may stand alone or be part of an elaborate hydraulic system linked to the vehicle towing the trailer or even to a trailer-based hydraulic system. Further, jacks may include mechanical gearing powered manually via the operator himself. Still further, jacks may include features of any combination of powering methods.
Common to all of the various types of prior jacks is some elongation of the jack body. Generally, one end of the jack will be fixed to the structure being lifted, supported, or leveled while the other end of the jack will be brought into contact with an immovable surface (i.e., a floor or earthen surface). Operation of the jack provides mechanical elongation of the jack body electrically, hydraulically, manually, or some combination thereof. This causes the structure such as a trailer to be displaced vertically, or otherwise supported vertically, in opposition to the immovable surface. If the immovable surface is not level, the vertical displacement may be termed as leveling such that the structure will become level when the jack is appropriately positioned. Several prior art systems for lifting and leveling exist which include these and other features and characteristics.
In the field of lifting and leveling, there have been attempts to provide stronger, more stable devices which elevate, support, or otherwise stabilize a movable structure. In general, the complexity of such efforts has undercut whatever advantages they might otherwise offer. Indeed, the time and effort involved in using complex and inefficient lifting and leveling devices is self-defeating. One related prior-art device is that of Sill et al. (U.S. Pat. No. 3,879,055), and involves stabilizing a camper-trailer. The device of Sill et al. is a set of telescoping supports that are pivotably mounted under a camper-trailer. Either support may fold up under the camper-trailer when not in use and are folded out and extended during use. As they are not designed to elevate the camper-trailer and are positioned at an angle to the ground, these supports are not able to provide any leveling features. Accordingly, the device of Sill et al. requires the camper-trailer to be placed on level ground and fails to provide any useful compensation for camper tilting.
There are, however, other prior-art devices similar to Sill et al. which do exhibit lifting and leveling capabilities. Such include the devices of Bruno et al. (U.S. Pat. No. 4,815,711), Valdespino (U.S. Pat. No. 4,216,939), and Hansen (U.S. Pat. No. 3,362,683). These three are devices that can stabilize a structure, such as a camper-trailer, with pivotable telescoping supports in a sufficiently powerful manner to provide compensation for any tilting of the structure. More particularly, the device of Bruno et al. is a hydraulic leveling device that has a hydraulic cylinder fixed in a vertical position via a clamp affixed to a surface of the structure to be leveled. The hydraulic cylinder has a pivot point at its telescoping end. Attached to the pivot point is a support foot that is able to pivot between an L-shaped position and an extended position that is parallel and aligned with the hydraulic cylinder. Such a design renders the device of Bruno et al. of limited use because the hydraulic cylinder is always in the vertical position. Even though the support foot is foldable, it is not fully retractable due to the location of the pivot point. Thus, when not in use the leveling device of Bruno et al. will tend to project away from the structure being leveled and pose a safety hazard or simply be more prone to damage.
The device of Valdespino is another leveling device which includes a set of hydraulic cylinders for leveling a camper-trailer. In this device, however, there is a support foot fixedly attached to the hydraulic cylinder's telescoping end. The other end of the hydraulic cylinder is pivotably attached to a bottom surface of the camper-trailer. When not in use, each support foot is linearly retracted by its respective hydraulic cylinder which is then pivoted together to a folded position against the camper-trailer. The device of Hansen is substantially similar to that of Valdespino except that the Hansen device provides that each hydraulic cylinder is foldable into a recessed encasement. A general defect of the devices of Valdespino, Hansen, and Bruno et al. is that none of these devices enable the cylinders to be readily moved around on the surface of the structure to be leveled. This lack of versatility is a by-product of the complex hydraulic systems that these three devices represent.
Concurrent with the development of the prior-art hydraulic lifting/leveling devices already mentioned, self-contained lifting devices have been developed with the goal of removability. Typically, such devices are bolted to a support-plate located somewhere along the periphery of the structure being lifted and/or leveled. This allows a linearly adjustable support to be mounted alongside the structure. Two representative prior-art devices are those of Bock (U.S. Pat. No. 4,784,369) and Mann (U.S. Pat. No. 3,709,467). The lifting device of Bock includes a base with telescoping tubes. The base is at one end removably bolted to a mounting bracket and at the other end fixed to a tripodal foot. A manually-operated crank raises and lowers the tripodal foot via the telescoping tubes. As the tripodal foot is extended against the ground surface, the structure to which the lifting device is bolted is raised. The device of Bock exhibits several flaws, including, most importantly, a lack of range in the telescoping distance. The mounting surface of the structure before being lifted can be no further off the ground than the non-extended length of the telescoping device. This aspect severely limits the mounting surface locations upon which the telescoping device may be placed.
The device of Mann includes an adjustable vertical support device similar to Bock but one having a removable hydraulic jack. Included in the Mann device are four vertical supports which are vertically adjustable by means of the hydraulic jack. As the hydraulic jack is removable, the jack may be used for raising and lowering each of the four vertical supports incrementally. Accordingly, the device of Mann is time-consuming in its operation. Further, while the jack is itself transferrable to each vertical support, the supports are not movable. Similar to Bock, the device of Mann is severely limited in its versatility because each of the four supports are fixed in their positions and cannot be readily moved so as to better adapt to uneven ground. Expense is added by having the supports each fixed to a corner. As well, safety is decreased because the supports are not secured to the structural frame.
In a related manner, those trailers having motorized mechanisms to lift or lower a trailer--particularly those trailers known as "fifth wheels," that is, those trailers having one or more jacks up front that are used to couple or uncouple the trailer from within or on a carrier vehicle, require a supplemental lifting means. In the event the gears from the motorized mechanism are stripped or otherwise rendered inoperable, the user cannot either move the fifth wheel into a coupling position with the vehicle, or he cannot uncouple it from the vehicle. In that regard, it would be useful to have a completely functional jack--or at least the capability to install a useable jack--at the front of such types of trailers as a backup for the costly and complex motorized mechanism.
Accordingly, the prior art fails to provide any vertically adjustable lifting device that is compact, portable, and readily adaptable to a wide range of lengths and lifting needs. Therefore, what is needed is a lifting device that provides a high degree of portability. What is also needed is such a device that is easily adaptable for use at multiple locations on a structure to be lifted or otherwise stabilized. What is needed is a lifting device that avoids complex gearing or electrical requirements so that it may be more reliably used at any given site. Further, what is needed is such a lifting device that ensures stable support of trailer structures. Still further, what is needed is a lifting system that departs from the complex and expensive nature of prior lifting devices. What is needed is such a system that can readily be attached at virtually any desired location, and assembled subsequent to manufacture of the structure being lifted.